Fixes bug where define.amd was not an object
Fixes bug where define.amd was not an object

This:
* is contrary to the AMD spec
    * https://github.com/amdjs/amdjs-api/wiki/AMD#defineamd-property-
* causes certain libraries to assume hazelnut is not an AMD loader.
    * They check if define.amd is an object, rather than merely checking if it's truthy
    * Not necessarily hazelnut's fault, but there's no harm in setting `amd = {}` instead of `= true`

developit/hazelnut